ABOUT THE SAD LIGHT INTENDED USEMedical intended use of this appliance is to treat the symptoms of SAD (seasonal affective disorder).r winter depression.“SAD Light” is intended t. boost people’s energy levels, to adjust circadian rhythms and make people feel m.re awake.“SAD Light” is safe and medically proven to provide relief from the symptoms of SAD. How Does the “SAD LIGHT” WORK. In autumn and winter, the seasons with the least sunlight because of shorter days, the lack of sunlight and a problem with certain brain chemicals stops the hypothalamus working properly. The lack of light is thought to affect the production of the hormo-ne melatonin (that makes you sleepy).“SAD Light” uses bright lights to simulate the sunlight during the darker autumn and winter, whilst eliminating the dangerous UV rays contained in sunlight. The additional light helps adjust the levels of melatonin that can help the symptoms of SAD.